From owner-freebsd-stable@FreeBSD.ORG Sat Oct 4 02:51:49 2014 Return-Path: Delivered-To: freebsd-stable@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 1B99FB9F; Sat, 4 Oct 2014 02:51:49 +0000 (UTC) Received: from smtp1.multiplay.co.uk (smtp1.multiplay.co.uk [85.236.96.35]) by mx1.freebsd.org (Postfix) with ESMTP id D4242F98; Sat, 4 Oct 2014 02:51:48 +0000 (UTC) Received: by smtp1.multiplay.co.uk (Postfix, from userid 65534) id A863220E7088B; Sat, 4 Oct 2014 02:51:46 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.multiplay.co.uk X-Spam-Level: ** X-Spam-Status: No, score=2.2 required=8.0 tests=AWL,BAYES_00,DOS_OE_TO_MX, FSL_HELO_NON_FQDN_1,RDNS_DYNAMIC,STOX_REPLY_TYPE autolearn=no version=3.3.1 Received: from r2d2 (82-69-141-170.dsl.in-addr.zen.co.uk [82.69.141.170]) by smtp1.multiplay.co.uk (Postfix) with ESMTPS id 202DA20E70886; Sat, 4 Oct 2014 02:51:44 +0000 (UTC) Message-ID: <64F0D761D09546C7B47DFAA1551500BE@multiplay.co.uk> From: "Steven Hartland" To: "Glen Barber" , References: <20141004024011.GC1199@hub.FreeBSD.org> Subject: Re: Heads-up: Possible regression between 10.0-RELEASE and 10.1-BETA1 with '/ on ZFS' setup Date: Sat, 4 Oct 2014 03:51:39 +0100 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5931 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.6157 Cc: FreeBSD Release Engineering Team X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 04 Oct 2014 02:51:49 -0000 ----- Original Message ----- From: "Glen Barber" > During testing of the 10.1-RC1, I set up a multi-disk VirtualBox VM to > test '/ on ZFS' in various scenarios. FreeBSD 10.1-RC1 i386, when > installed on ZFS with more than one disk (i.e., mirror, raidz-1, > raidz-2, etc.) crashes when rebooting post-install. > > This does not happen with a single-drive '/ on ZFS' setup under the same > configuration. > > FreeBSD 10.0-RELEASE i386 does not exhibit this behavior, however > upgrading from 10.0-RELEASE to 10.0-BETA1 or later may exhibit > a double-fault panic on boot. > > A possible solution to this is to set kern.kstack_pages=4 via loader(8), > however in my tests (solely in VirtualBox), this has been ineffective. > > It is unclear to me right now if this is something specific to > VirtualBox or not, though this problem was reported recently through > Bugzilla ( https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=194015 ). > > I am still bisecting the stable/10 tree to try to identify when this > possible regression was introduced, in addition to scrounging up the > hardware to be able to test this on a bare-metal machine to determine if > this is a VirtualBox (or hypervisor in general) specific problem, but > this is taking longer than initially expected. > > To be perfectly clear, the panic does occur in my particular testing > environment as far back as 10.1-BETA1, so this is *not* something new to > the upcoming 10.1-RC1. > > If you have a multi-drive '/ on ZFS' setup (mirror, raidz-1) *without* > PAE, and have upgraded to 10.1-BETA1 or later, please speak up in case > this is a problem specific to my testing environment, which will likely > be at least another day before I can verify is the case. This has been a known issue on i386 since the switch to Clang see UPDATING: 20121223: After switching to Clang as the default compiler some users of ZFS on i386 systems started to experience stack overflow kernel panics. Please consider using 'options KSTACK_PAGES=4' in such configurations. In my experience your millage may vary but essentially without 4 stack pages all bets are off in terms of stability. Regards Steve